Distinct methylalumoxane(MAO)-derived Me-MAO- anions in contact with a zirconocenium cation--a 13C-NMR study |
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| Authors: | Babushkin Dmitrii E Naundorf Corinna Brintzinger Hans H |
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| Institution: | Boreskov Institute of Catalysis, Russian Academy of Science, RU-630090, Novosibirsk, Russia. dimi@catalysis.nsk.su |
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| Abstract: | Zirconocenium cations of the type (MeC5H4)2ZrMe]+, formed by excess methylalumoxane (MAO) from (MeC5H4)2ZrCl2 or (MeC5H4)2ZrMe2 with 13C-labelled ring ligands, are found to form ion pairs with two types of anions, Me-MAO(A)- and Me-MAO(B)-, which differ in their coordinative strengths: More strongly coherent ion pairs (MeC5H4)2ZrMe+...Me-MAO(B)-] are converted to more easily separable ion pairs (MeC5H4)2ZrMe+...Me-MAO(A)-] by a sufficient excess of MAO. These react with Al2Me6 to form outer-sphere ion pairs containing the cationic AlMe3 adduct (MeC5H4)2Zr(mu-Me)2AlMe2]+; formation of the more easily separable ion pairs might be required also for polymerisation catalysis. |
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